1. Field of the Invention
The present invention relates to mouthpieces which are used in underwater breathing devices such as snorkels and regulators and to mouthpieces which are used in inhalators and gastric tubes for medical treatment.
2. Description of the Prior Art
The closest prior art known to applicant are U.S. Pat. Nos. 4,664,109, 4,466,434 and 4,136,689. Each patent shows a mouthpiece of the general type proposed by the present invention. U.S. Pat. No. 4,664,109 shows a mouthpiece which is symmetrical on its upper and lower surfaces with bite lugs which are of constant thickness and width. U.S. Pat. No. 4,466,109 shows an asymmetrical mouthpiece with an offset between the upper and lower surfaces. Bite lugs are shown which are of constant thickness and width and which are connected to each other by a ledge which firms the offset between the upper and lower surfaces to form a place for the upper front teeth to rest. The ledge thus formed is about 40 mm in width.
The prior art does not provide a device which the jaw structure shown in U.S. Pat. No. 4,466,434 is permitted to be in the normal mating bite position without continuing muscle tension. In particular the ball joint shown in FIG. 1 of the U.S. Pat. No. 4,466,434 is not kept in a normal rest position by any of the devices disclosed in the patents described above or by any other art known the applicant. In addition the prior art does not show an offset mouthpiece which is adaptable for both overbite and underbite conditions. The U.S. Pat. No. 4,466,434 device cannot be used with comfort in an underbite condition because of the ledge formed between the bite lugs.